In the latest remarkably developed information society, a convenient indexing of the extensive amount of information together with the filing and the efficient retrieval thereof when desired is required. For example, the information retrieval systems with use of a computer for literature, patent publications, news and the like have been placed in practical use.
Hitherto, there has been provided an information retrieval system in which information is indexed with keywords for memory in the memory device and the keyword is retrieved for extraction of the desired information. In the information retrieval system of this type, an accurate grasp of the relation between each of the keywords is required to perform retrieval of high quality.
Generally, the relationship between keywords include such relationships as those between synonyms; for example; the electric calculator and the computer, the broader term and the narrower term for example the computer and the microcomputer, the semi-synonym and a related words and the like and those relations may be consolidated into the so-called thesaurus.
The thesaurus is usually made into a book form so that the information retrieval may be performed by manually turning over the leaves of the book which is however cumbersome in transaction and rather disturbs its incorporation with the filing system and an efficient information retrieval.
It has now been found that a retrieval of the thesaurus of large scale may be conveniently performed by an improved information retrieval device in which keywords are coded to prepare, in relation to the thesaurus, a keyword relation table which includes identification keywords and their related keywords. The identification keyword of the keyword relation table of the identical heading characters are collected into a group to provide an index table in which a start address and an end address are defined, a word table in which the characters of the keyword and the codes are arranged in contrast, and a keyword relation table. The index table and the word table, thus prepared, are stored in a memory device so that the desired keyword may be retrieved from the foregoing tables with use of a convenient computer system.
An information retrieval device according to the invention may be comprised of an input device such as a keyboard, a thesaurus retrieving section with a microcomputer accommodated therein, memory devices for storing a keyword relation table, an index table and a word table respectively, a thesaurus control unit with a microcomputer accommodated therein to issue a retrieval instruction directly to each memory device and an output device of CRT display.
In accordance with the information retrieval device of the invention, a thesaurus of large scale may be stored despite the use of a relatively simple circuit arrangement and the retrieval control system may be more simplified to ensure a convenient operation of the device.